Sira started his career as an actor in the UK at a tender age of nine where he worked with Rosemary Leach and Ben Kingsley as a "Beggar Boy" in The Velvet Glove (1977) - The Warrior's Return (1977)_ a series for the BBC, directed by Philip Saville. Puneet went on to star alongside Christopher Lee, Mickey Rooney, Oliver Tobias, Emma Samms and Peter Cushing in the feature film Arabian Adventure (1979). Sira played the lead role of "Majeed", directed by Kevin Connor. In the same year Puneet played "Kasava Minor" in the BBC series To Serve Them All My Days (1980).

In 1979 Sira was the youngest member to participate in 'Comex 10', a commonwealth expedition sponsored by the Prince Philip, Duke of Edinburgh. Founded by Lieutenant Colonel Lionel Gregory, OBE, 'Comex 10' was an expedition where forty artistes from all commonwealth countries toured all of India performing variety acts in every city visited.

A vast body of work is credited to Sira during his tenure as an Assistant Director at the BBC Drama Films Dept. Sira became an Asst Director on films such as _"Screen Two" - Hallelujah Anyhow (1991)_ (BBC) starring Keith David and George Harris. "Screen One" - Sweet Nothing (1990) (BBC) and _"Screen One" - Can You Hear Me Thinking? (1990)_ starring Judi Dench, and freelanced on 'Flying Colours' (1992), Memsahib Rita (1994) (BBC), 'Blue Baby' (1994) before venturing into directing his own films like 'Strings' (1996) which he also wrote and produced.

Sira was also the director of 'The London Academy of Acting' (an acting school founded by his father, Gurdial Sira in 1970), where he would teach acting for film. He also set up his own Actors Agency, 'Talent Introduction Centre (T.I.C.)', where he would provide work for Asian Actors within the UK.

Casting Director was another title to Sira's credit, features films such as Jinnah (1998) starring 'Christoper Lee', _Flight (1995)_ (BBC Screen One), Directed by Alex Pillai, Immaculate Conception (1992) Directed by Jamil Dehlavi, Memsahib Rita (1994) (BBC) and Frantz Fanon: Black Skin, White Mask (1995) Directed by Isaac Julien. On the American feature film Passion in the Desert (1997) Sira worked on production.

Sira also lectured on Basic film making at Middlesex University and Italia Conti Acting Academy as a visiting lecturer.

In 1998, Sira became the Executive Producer for Rupert Murdoch's 'Channel V', (Star TV), producing more than twenty two television shows for the channel in Mumbai. He went on to produce and direct drama for television The Steal (2000) (Star TV), followed by Sanatta (2003) and Jataka Tales (2003) for Japanese television which Sira Directed and Produced with his partner Vikram Dhillon. Sira went on to Direct the feature films I Proud to Be an Indian (2004), Jai Veeru: Friends Forever (2009) and Kisaan (2009).

As a screenwriter Sira wrote I Proud to Be an Indian (2004) with Vekeana Dhillon, together they have written the screenplay for the feature film Kurbani for Feroz Khan (FK International) and 'Spiceboy' for Miracle Films. Sira had also written The Steal (2000) and Sanatta (2003).

Sira and Vikram Dhillon are partners in Eyeline Entertainment a production company which has several feature films in development and in production, Ji Karda a love story being Directed by Vikram Dhillon and Produced by Sira. In development are 'Afflicted', 'Delirium' and 'Case No.1.' to be directed by Sira and produced by Sira and Vikram Dhillon.